[Bioc-sig-seq] adding columns to values of GenomicRange objects

[Jiang, Lichun (NIH/NIDDK) [F]]

Hi Dear all,
    I am a newbie using GRanges and related packages. Try to figure out how can I add an column of values to the GenomicRanges.

For example I get a object named as TF_peaks:

GRanges with 2000 ranges and 3 elementMetadata values
    seqnames                 ranges strand | elementMetadata.polIIsignal elementMetadata.inputSignal elementMetadata.enrichment
       <Rle>              <IRanges>  <Rle> |                   <integer>                   <integer>                  <numeric>
[1]     chr1 [205566106, 205576720]      * |                        1504                           4                   382.2567
[2]     chr1 [ 11890546,  11892791]      * |                        1140                           4                   347.6909
....

I tried to add another value to describe whether this features are overlapping with promoters(I already has this value as inpromoteres for example ).
But I can't add this value to the TF_peaks object by standard function for dataframe manipulation. I guess I am not fully understand the S4 methods.  Anyone can help me out?

Thanks,
Lichun